First try at candling

Ok all of you have inspired me to try my hand at candling. I have red rocks in the incubator right now, day 10. I candled tonight and 38 of the 42 have veins through the egg, and I can see a dark area moving in them, I am so excited. 2 of the other eggs are clear, they have small cracks in them that I can see when I candle them, the other two have viens but they are in a circle around the top of the egg and nothing moving inside. Should I get rid of the 4 bad ones?
Another question, I tried this cross last year and of the 22 that hatched we had to put down 10 of the females because they had bad legs, they couldn't extend them out to walk, I felt so bad. Would it be something I am doing wrong with the bator, genetics? If someone could give me some insite I would like to fix whatever I did wrong so these little guys are ok when they hatch.

The leg thing could be caused by Incubation temp too high,Moisture too low, or Improper turning and setting. It could also be caused by putting babys on a slick surface before they can fully develop. Hopefully someone with more experience can answer that.

I will take the bad ones out and see what they look like inside. As for the leg problems, I have an automatic turner so they should be turning fine, it could have been temp or humidity, I have a regular hovabator and I used to have it in the basement last year where the temps are colder and fluctuate a bit more, this year it is in the kitchen so hopefully everything works out better.
Thanks for the help.